Microwave communication systems (e.g., satellite based communications, etc.) are popular, especially where asymmetrical digital subscriber lines (ADSL) and cables are not available. By way of example, Fixed Service Satellite (FSS) systems have huge capacities with a relatively economical price structures, and the FSS systems provide various applications for subscribers, such as, telephony, fax, television, high speed data communication services, Internet access, satellite news gathering (SNG), digital audio broadcasting (DAB), etc.
In the prior art, an Inter-Facility Link (IFL) for satellite terminals in a Very Small Aperture Terminal (VSAT) application transmits data from an indoor unit to an outdoor unit using a data modulated L-band carrier and the outdoor unit up-converts or multiplies the data modulated L-band carrier to a higher frequency using a fixed constant, prior to transmission to the satellite. The integrity of the data modulated L-band carrier is affected by the cable length between the modem and the outdoor unit, and the integrity of the data modulated carrier transmitted over the IFL cable is not evaluated and/or corrected prior to transmission to the satellite. Moreover, there is no control communication between the in-door unit and the out-door unit as no processing is done by the ODU.
The transmitting of a signal from the IDU to the ODU requires extensive tuning of the IFL between the IDU and the ODU, for example, to equalize the signal for cable length of the signal from the IDU and ODU. In a transmit mode, the signals from the IDU to the ODU may have picked up extraneous signals (“noise”), unless the IFL connecting the IDU and the ODU are tuned. Without tuning the cable, the radio in the ODU amplifies/boosts the signal to be transmitted along with amplifying the noise signals and up-converts the frequencies of the signals to be transmitted into higher frequencies. The tuning of the IFL incurs installation costs.
In addition, for linear radio transmissions, the reception and transmission frequency bands overlap and the prior art IFL requires two cables, one cable for receiving and one cable for sending, and each cable may need to be separately tuned. Lastly, in the prior art, radio components are dispersed between the IDU and ODU, rather being disposed entirely, for example, in the ODU.